1. Field of the Invention
The present invention relates to a device for preventing fluid free flow through a tube assembly of a fluid administration system, and more particularly to an anti-free flow valve device which is incorporated into a drip chamber of the fluid administration system. More specifically, the present invention relates to an anti-free flow device that prevents fluid free flow when the tube assembly is disengaged from a pump, while allowing fluid flow when the tube assembly is engaged with the pump.
2. Prior Art
Administering fluid, such as medication, saline and nutritional formula, to a patient is well known in the art. Typically, fluid is supplied to a patient by a tube assembly of a fluid administration system which provides a fluid pathway between a fluid source and a patient. The fluid is supplied to the patient through the tube assembly by either an enteral connection which accesses a visceral organ (gastrointestinal feeding) of a patient or through a parenteral connection which accesses a non-visceral organ (intravenous feeding).
Fluid flow rate through the tube assembly may be manually controlled by a mechanical clip which is designed to progressively occlude the tube assembly and selectively impede fluid flow induced by gravity. One such mechanical clip which operates to occlude a portion of the tube assembly is a conventional roller clamp that has a hollow body with opposed openings and a pair of angled slots formed opposite of one another transverse to the openings. The clip further includes a wheel having an axle which is coupled to the body through the slots. A portion of the tube assembly is then inserted through both the openings of the roller clamp and the wheel axially advanced along the slots to pinch a portion of the tube assembly against the body which progressively occludes the tube assembly. Although the mechanical clip operates to provide a cost efficient method for controlling fluid flow rate, the clip must be manually actuated by the user. Further, the wheel of the mechanical clip can be inadvertently bumped or jostled out of position resulting in an inappropriate flow rate.
In order to better enhance fluid flow rate control in a fluid administration system, calibrated pumps have been utilized. One such calibrated pump is a peristaltic pump connected in-line along a portion of the tube assembly between the fluid source and the patient. The peristaltic pump advances the fluid through the tube assembly by progressively occluding successive portions of the tube assembly and urging each occluded portion forward by rotating the rotor of the pump. When a peristaltic pump is utilized to control the fluid flow rate, mechanical clips are typically not employed or are disengaged to prevent the clip from interfering with the operation of the pump.
Although peristaltic pumps have substantially advanced the art, further improvements are required. For example, once the tube assembly is disengaged from the rotor of the pump fluid flow rate through the tube assembly becomes unrestrained as fluid is drawn through the tube assembly by the force of gravity. This situation is known as fluid free flow and may present an undesirable or even life-threatening situation if left undetected because of the risk of overfeeding or overmedicating a patient.
In order to overcome the above-noted drawbacks to fluid administration systems utilizing pumps, several devices have been suggested which operate to automatically occlude a portion of the tube assembly and prevent fluid free flow when the tube assembly becomes disengaged from the rotor of the pump while also permitting uninhibited fluid flow when the tube assembly is properly engaged to the pump. For instance, a variety of automatic occluders have been suggested to improve the art such as those disclosed in U.S. Pat. No. 4,689,043 to Bisha entitled "IV Tube Activator" which describes a clamp for use with a peristaltic pump. The clamp includes a V-shaped channel which is spring biased into a closed position where the narrow portion of the V-shaped channel is sized to substantially crimp, or occlude, a portion of the tube assembly and prevent fluid free flow therethrough. The clamp is placed in an open position by a handle which overlays the pump and depresses the springs such that the tube assembly is positioned within the wider portion of the V-shaped channel to permit unrestricted fluid flow through the tube assembly when the pump is operating. When the handle is released, the V-shaped portion will automatically slide into the closed position and prevent fluid free flow by occluding a portion of the tube assembly.
Another automatic occluder is disclosed in U.S. Pat. No. 5,704,582 to Winterer, et al. entitled "Pinched Clipped Occluder for Infusion Sets" which describes a clip that is positioned between a housing and a cover of a pump. The clip has a plunger biased by a spring against the lumen of the tube assembly so that the lumen becomes occluded by the plunger. Fluid flow through the tube assembly may only be established when the plunger is biased away from the lumen of the tube assembly which occurs when the cover is properly coupled with the housing. However, once the cover becomes disengaged from the housing, the plunger is automatically biased into the closed position by the spring to prevent fluid free flow.
Although both of the aforementioned automatic occluders have advanced the art, both devices are mechanically complex and prone to mechanical failure. In addition, the mechanical complexity of these devices also results in occluders which are expensive to manufacture. Accordingly, there is a need in the art for a valve device which forms an integral part of the tube assembly that is capable of preventing fluid free flow when the tube assembly is disengaged from the pump, while also being mechanically uncomplicated, reliable and low cost to manufacture.